In some pathological states such as therosclerosis tissue destruction may be accelerated due to uncontrolled protease release of polymorphonuclear leukocytes and other events such as decreased concentration and/or the inactivation of main protease inhibitor molecules in the serum. In this study, the authors measured the elastase release of polymorphonuclear leukocytes which increased in atherosclerosis independently of the patients aged compared to healthy young subjects. These findings were similar to the response of polymorphonuclear leukocytes separated from healthy elderly subjects. Simultaneously, the main plasma proteinase inhibitors such as alpha-1-antitrypsin and alpha-2-macroglobulin in healthy and atherosclerotic subjects were determined. alpha-1-antitrypsin did not decrease significantly, whereas alpha-2-macroglobulin did in sera of atherosclerotic patients compared to age matched subjects (p < 0.05). In contrast, the activity of porcine pancreatic elastase was more effectively neutralized by the plasma obtained from healthy subjects suggesting diminished antiprotease activity of sera obtained from patients. The authors concluded that increased elastase release and decreased antiproteinase activity should be considered in atherosclerotic arterial wall damage. The similarity of the results in aged and therosclerotic subjects suggests that arteriosclerosis is an earlier aging process.